*{
	margin: 0;
	padding: 0;
	box-sizing: border-box;
}
.container{
	width: 1200px;
	margin: auto;
}
.col{
	float: left;
	width: 30%;
	height: 100px;
	background-color: mediumpurple;
}
.container::after{
	content: "";
	display: table;
	clear: both;
}
@media (max-width:600px) {
	.col{
		width: 100%;
	}
	.container{
		width: 100%;
	}
	
}